In the field of preparing food, many appliances are available which are intended to facilitate processes involved with cooking. For example, when a person wants to roast pieces of meat and has to perform this process in a conventional manner, he/she is compelled to take a pan, to fill the pan with the pieces of meat and probably also some oil or the like, and to put the pan on a stove and activate the stove for heating the content of the pan. Furthermore, the person needs to stir the pieces of meat, at least from time to time, by means of a suitable stirring tool, in order to avoid uneven cooking and possible scorching of the pieces of meat. Hence, the person needs to play a very active role in the cooking process and has no other choice but to stay in the kitchen until the food is ready. However, it is also possible to use a special appliance for performing the cooking process, which is especially adapted to function without any human intervention after having been filled with the ingredients as desired and being switched on. In that case, a person does not need to stay in the kitchen for a long time and has an opportunity to spend more time with family and/or friends, for example.
US 2008/190301 discloses an example of a special appliance as mentioned. In particular, US 2008/190301 relates to a stir cooker which comprises a container having an open top and a sidewall for holding food, a lid for closing the open top of container, a stirrer installed inside the container for stirring food, co-rotation prevention members installed inside the container on the sidewall for preventing food pieces from co-rotating with the stirrer, as the stirrer rotates, a heating tube fixedly installed on a bottom of the container for heating food, a base support disposed underneath the container for supporting the container, a support member installed on the bottom of the container for adapting the container to stand in position on the base support, and a motor installed inside the base support and removably coupled with the stirrer for driving the stirrer to stir food.
According to the teaching of US 2008/190301, the heating tube is fixedly installed on the bottom of the container to save some cost associated with a heater having a thermal diffusion plate, which requires significant amount of material and space. Also, it is stated that by directly installing the heating tube on the bottom of the container, heating efficiency is significantly enhanced. The profile of the stirrer is optimized for minimizing stirring resistance, such that less motor power is required to drive the stirrer, which saves some cost on motors.
The co-rotation prevention members of the stir cooker include a rib-shaped elongated member that extends generally vertical along the sidewall of the container. The upper ends of the members extend substantially to the upper portion of the container. The members are preferably disposed substantially dose to handles of the container such that the members would not obstruct food unloading. The members extend inward to a predetermined distance, away from the sidewall of the container. The predetermined distance is determined based on the size of the container. Proper clearance between the members and the stirrer should be maintained. When food co-rotates with the stirrer and runs against the members, as the stirrer rotates, food pieces at a higher level close to the members would be stopped and tumbled down due to gravity, resulting in better mixing or stirring of food, thereby facilitating heat transfer to and uniform heating of food.
As mentioned in the foregoing, a motor is installed inside the base support for providing rotation power to the stirrer. The motor is removably coupled with a drive shaft, as the container is installed in position. The drive shaft is threaded through a central aperture on the bottom of the container. The upper end of the shaft is engaged with the stirrer, and the lower end of the shaft is coupled with the motor through a coupling device. A seal device is provided for sealing off the interface between the shaft and the bottom of the container.
Even though the stir cooker known from US 2008/190301 has the advantage of being an automatic cooking appliance, there are a number of apparent disadvantages associated with this appliance. For example, the fact that the heating tube is installed directly on the bottom of the container makes it difficult for a user of the stir cooker to clean the container after use. In US 2008/190301, it is stated that the container is convenient for cleaning after use and dishwasher safe, but the fact is that not all surfaces of the container have a smooth appearance. The bottom side of the container where the heating tube is present is one example of an uneven surface, whereas the inner side of the sidewall of the container is another example, due to the presence of the co-rotation prevention members. Another disadvantage resides in the fact that the arrangement of the shaft for driving the stirrer is such that a seal device needs to be used in the container.